Border Patrol spokesman Henry Mendiola declined to specify if the two aerostats had helped in seizing drugs or illegal immigrants. However, he said the balloons floating near Roma have been an effective new surveillance tool for agents.

Agents offered a glimpse of the capabilities Wednesday to media and government officials.

The devices are on loan from the Defense Department so that Customs and Border Protection can study whether they should be added to the its arsenal of border monitoring equipment. That arsenal already includes airplanes, helicopters, drones, ground-based sensors and agents.